res_timing: Don't close FD 0 when out of open files.

This fixes so a failure to get a timer file descriptor does not cascade
to closing FD 0.

On error, both res_timing_kqueue and res_timing_timerfd would call the
destructor before setting the file handle. The file handle had been
initialized to 0, causing FD 0 to be closed. This in turn, resulted in
floods of "CLI>" messages and an unusable terminal.

ASTERISK-19277 #close
Reported by: Barry Chern

For the 13 branch, this was already fixed. This patch only ensures that
we do not attempt to close a negative file descriptor.

Change-Id: I147d7e33726c6e5a2751928d56561494f5800350

res/res_timing_kqueue.c

@@ -159,7 +159,9 @@ static void timer_destroy(void *obj)
 	struct kqueue_timer *timer = obj;
 	ast_debug(5, "[%d]: Timer Destroy\n", timer->handle);
 	kqueue_timer_fini_continuous_event(timer);
-	close(timer->handle);
+	if (timer->handle > -1) {
+		close(timer->handle);
+	}
 }
 
 static void *kqueue_timer_open(void)

res/res_timing_timerfd.c

@@ -76,8 +76,9 @@ struct timerfd_timer {
 static void timer_destroy(void *obj)
 {
 	struct timerfd_timer *timer = obj;
-
-	close(timer->fd);
+	if (timer->fd > -1) {
+		close(timer->fd);
+	}
 }
 
 static void *timerfd_timer_open(void)